Meet the Amazon river dolphin (Inia geoffrensis), also known as the boto, or, if you believe Amazonian folklore, dad. Legend has it that the dolphin can transform itself into a handsome young man, who is a willing dance and conversation partner for village women. The enchanted dolphin is blamed - somewhat conveniently, it has to be said - for children whose paternity is disputed.

Now we know a little more about the animal - but not much. It lives in the Amazon and Orinoco rivers, but we don't have a good estimate of population size because its habitat range is vast and the rivers are mostly inaccessible. Despite this, it is listed by the International Union for Conservation of Nature as an endangered species. Many boto are killed by fishermen, pollution, boat traffic accidents and habitat loss, which are factors that drove the Chinese river dolphin, the Baiji, to almost-certain extinction.

The boto - the largest of the four remaining species of river dolphin - is well adapted to its murky environment. Unfused vertebrae in its neck mean it is capable of turning its head through a range of 180 degrees, allowing it to squeeze around submerged trees and roots. Its long snout means it can winkle out hiding fish, crabs and turtles.

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As for why it is so delicately coloured, we don't know for sure. A network of capillaries at the surface of the skin may explain it.

Image: Kevin Schafer/naturepl.com. This post originally appeared on New Scientist.